Applying Scientific Methods
Name ________________________
Period _____ Date ______________
Milkweed is a plant commonly found throughout fields and pastures
and along roadsides in eastern and central North America. It gets its
name from the milky white sap that oozes when the plant is broken or
cut. Milkweed plants bloom in June and July. When fertilized, the
flowers form large seedpods that open in the fall. The following
observations were taken from a scientist's field study of milkweed
plants from spring through fall.
In the summer, the sugary nectar secreted by the milkweed's
flowers attracts many bees, butterflies, moths, and a variety of
smaller insects that carry away pollen when they depart. Milkweed
nectar seems to be the major source of nutrition for several species
of small moths, flies, mosquitoes, and ants. Monarch butterflies, which
visit in large numbers, lay their eggs on milkweed plants, and the
hatching caterpillars feed on the leaves. As fall approaches, milkweed
bugs begin to attack the developing seeds, and milkweed beetles eat
the foliage.
Aphids, which suck milkweed sap, are found throughout the year.
Crab spiders do not feed on the plant itself, but rather on most of the
insects that visit the plant. In the two to three weeks while the
milkweed plants are in bloom, successful adult female crab spiders may
increase ten times in mass before laying their eggs on the inner
surface of leaves. Some species of flies and wasps, which feed on crab
spider eggs, visit the plants periodically. Harvestmen, also known as
"daddy longlegs," eat the remains left by predators.
Please answer questions on the other side.
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1. Did this scientist perform quantitative or qualitative research?
2. What level of organization in an ecosystem is represented by the milkweed and the organisms that visit or live on the plant?
3. Based on the scientist's observations, draw one food chain that begins with a milkweed plant. Include at least four organisms.
4. What is the niche of the harvestman?
5. How would you describe the symbiotic relationship between the milkweed plant and aphids?
(what type of symbiosis & what are the two doing to each other)
6. Based on the scientist’s observations, formulate a hypothesis about the effects of crab spiders on the survival of the milkweed plant.
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